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研究了MgO-C质材料中添加纳米镍改性酚醛树脂后,原位催化形成纳米碳(碳纳米纤维和碳纳米管)的可能性。FE-SEM显微形貌显示,在800~1 200℃热处理温度范围内,纳米镍改性酚醛树脂热解过程中形成了纳米碳结构。此外,1 000℃及更高温度下热处理后MgO-C试样基质中生成了纳米碳结构,当温度升高到1 200℃后,促进气孔中生成了纳米碳结构。含1%镍改性酚醛树脂的MgO-C基质试样具有最好的物理和力学性能。当热处理温度从800℃升高到1 200℃,试样的常温抗折强度仅降低了15%。并且,1 200℃烧后试样的体积密度增大了6.5%,显气孔率降低了10%。原位生成纳米碳结构之所以能够改善试样的力学性能是因为其阻碍了裂纹的产生。
The possibility of nano-carbon (carbon nanofibers and carbon nanotubes) formed by in-situ catalysis after adding nano-nickel modified phenolic resin into MgO-C material was studied. The FE-SEM micrographs showed that the nanocarbon structure was formed during the pyrolysis of nano-sized nickel-modified phenolic resin in the temperature range of 800 ~ 1 200 ℃. In addition, the nano-carbon structure was formed in the matrix of MgO-C after heat treatment at 1000 ℃ and higher, and the nano-carbon structure was promoted when the temperature increased to 1 200 ℃. The MgO-C matrix specimens with 1% nickel modified phenolic resin have the best physical and mechanical properties. When the heat treatment temperature is raised from 800 ℃ to 1200 ℃, the room temperature bending strength of the sample is reduced by only 15%. Moreover, the bulk density of the sample after burning at 1 200 ℃ increased by 6.5% and the apparent porosity decreased by 10%. The reason why in-situ formation of nano-carbon structure can improve the mechanical properties of the sample is because it hinders the generation of cracks.